Hydration strategy in sports has evolved from simplistic recommendations to highly individualized protocols based on sweat rate, sweat sodium concentration, environmental conditions, and exercise duration. Both under-hydration and over-hydration (exercise-associated hyponatremia) carry performance and health risks.
Performance Impact of Dehydration
The physiological effects of exercise-associated dehydration begin at approximately 2% body weight loss: cardiac output decreases as plasma volume falls, core temperature rises faster, and central fatigue develops. Meta-analyses show 2% dehydration reduces aerobic performance by 5–10% and time-to-exhaustion performance by up to 15%. Cognitive performance impairs at even lower levels — 1–1.5% dehydration — affecting decision-making and reaction time relevant to team sports and motor skill execution.
Sodium: The Critical Electrolyte
Sweat sodium concentration varies 2–3 fold between individuals (230–1750 mg/L). Replacing fluid without sodium during prolonged exercise dilutes plasma sodium and risks exercise-associated hyponatremia (EAH) — a potentially fatal condition. Sodium replacement during exercise exceeding 60–90 minutes: aim for 500–1000mg sodium/hour from sports drinks, sodium tablets, or electrolyte gels. Electrolyte products and clinical sodium supplementation options are in our nutrition catalog.
